1. Field of the Invention
The invention relates to display devices of the type where the information is displayed on a flat panel, the type of information to be displayed being selected by the operator.
2. Description of the Prior Art
In aircraft, information such as the operational variables and parameters of the various items of on-board equipment is displayed by means of standard instruments such as graduated dials, meters, indicators, etc. and also, increasingly, through images obtained by means of cathode ray tubes, plasma panels, light-emitting diodes, electroluminescent panels or liquid crystal display devices. These image display devices enable the depiction of several parameters on one and the same surface, either simultaneously or successively or, at the operator's request, thus reducing the number of standard instruments on the dashboard.
A further advantage of these image displaying devices is that they can be placed at a large distance, from both the instruments for which they display the parameters and from the electronic circuits which control the preparation of the images and/or the display of information, thus making it easier to place them in the most suitable position for the operator.
The above two aspects, namely the display of several different items of information on one and the same screen and the remote control of the display of said information leads to a more efficient use of the available volume which, in principle, is reduced to the maximum extent in an aircraft, especially in the vicinity of the pilot.
For the operator in front of a display device of this type, it is important that he should be able to display the maximum amount of information on a single device, but he is limited by the size of the screen.
An aim of the invention, therefore, is to make a flat panel display device that enables the operator to select only that type of information which he wishes to display, for example information relating to the engine or information relating to the hydraulic circuits etc., by pressing one of the keys associated with the screen, each key corresponding to a certain type of information.
Of course, it is desirable for the number of keys to be limited for reasons of space and handling ease, and this reduces the total amount of information that can be displayed on one and the same device.
Another aim of the invention, then, is to make a flat panel display device in which the number of selection keys does not constitute a limit on the displaying possibilities of said device, this aim being achieved by stipulating several meanings per key, which are displayed successively on the screen at the operator's request.
In the event of failure of the flat screen as well as in circumstances where a number of the aircraft instruments work in back-up mode, it is important for the operator to be capable of displaying the essential parameters, even if it is only in simplified form.
Thus, another aim of the invention is to make a flat panel display device wherein there is provision for a back-up mode of operation.
As mentioned above, there is little space available, in the aircraft near the pilot, to set up a display device of this type. Consequently, another aim of the invention is to make a compact flat panel display device.